﻿<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright 2012 Eric Niebler

  Distributed under the Boost
  Software License, Version 1.0. (See accompanying
  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  -->
<header name="boost/proto/eval.hpp">
  <para>
    Contains the
    <computeroutput>
      <functionname alt="boost::proto::eval">proto::eval()</functionname>
    </computeroutput> expression evaluator.
  </para>
  <namespace name="boost">
    <namespace name="proto">
      <namespace name="functional">
        <!-- proto::functional::eval-->
        <struct name="eval">
          <purpose>A <conceptname>PolymorphicFunctionObject</conceptname> type for evaluating a given Proto
            expression with a given context.</purpose>
          <inherit>
            <type><classname>proto::callable</classname></type>
          </inherit>
          <struct-specialization name="result">
            <template>
              <template-type-parameter name="This"/>
              <template-type-parameter name="Expr"/>
              <template-type-parameter name="Context"/>
            </template>
            <specialization>
              <template-arg>This(Expr, Context)</template-arg>
            </specialization>
            <inherit>
              <type>
    <classname>proto::result_of::eval</classname>&lt;
      typename boost::remove_reference&lt; Expr &gt;::type, 
      typename boost::remove_reference&lt; Context &gt;::type 
    &gt;</type>
            </inherit>
          </struct-specialization>
          <method-group name="public member functions">
            <method name="operator()" cv="const">
              <type>typename <classname>proto::result_of::eval</classname>&lt; Expr, Context &gt;::type</type>
              <template>
                <template-type-parameter name="Expr"/>
                <template-type-parameter name="Context"/>
              </template>
              <parameter name="expr">
                <paramtype>Expr &amp;</paramtype>
                <description>
                  <para>The Proto expression to evaluate.</para>
                </description>
              </parameter>
              <parameter name="context">
                <paramtype>Context &amp;</paramtype>
                <description>
                  <para>The context in which the expression should be evaluated. </para>
                </description>
              </parameter>
              <purpose>Evaluate a given Proto expression with a given context. </purpose>
              <returns>
                <para>
                  <computeroutput>typename Context::template eval&lt;Expr&gt;()(expr, context)</computeroutput>
                </para>
              </returns>
            </method>
            <method name="operator()" cv="const">
              <type>typename <classname>proto::result_of::eval</classname>&lt; Expr, Context &gt;::type</type>
              <template>
                <template-type-parameter name="Expr"/>
                <template-type-parameter name="Context"/>
              </template>
              <parameter name="expr">
                <paramtype>Expr &amp;</paramtype>
              </parameter>
              <parameter name="context">
                <paramtype>Context const &amp;</paramtype>
              </parameter>
              <description>
                <para>
                  This is an overloaded member function, provided for convenience. It differs from the above
                  function only in what argument(s) it accepts. 
                </para>
              </description>
            </method>
          </method-group>
        </struct>
      </namespace>
      <namespace name="result_of">
        <!-- proto::result_of::eval -->
        <struct name="eval">
          <template>
            <template-type-parameter name="Expr"/>
            <template-type-parameter name="Context"/>
          </template>
          <purpose>A metafunction for calculating the return type of <computeroutput>
              <functionname alt="proto::eval">proto::eval()</functionname></computeroutput> given a
              certain <computeroutput>Expr</computeroutput> and <computeroutput>Context</computeroutput> types.</purpose>
          <typedef name="type">
            <type>typename Context::template eval&lt; Expr &gt;::result_type</type>
          </typedef>
        </struct>
      </namespace>
      <!-- proto::eval() -->
      <overloaded-function name="eval">
        <signature>
          <type>typename <classname>proto::result_of::eval</classname>&lt; Expr, Context &gt;::type</type>
          <template>
            <template-type-parameter name="Expr"/>
            <template-type-parameter name="Context"/>
          </template>
          <parameter name="expr">
            <paramtype>Expr &amp;</paramtype>
            <description>
              <para>The Proto expression to evaluate.</para>
            </description>
          </parameter>
          <parameter name="context">
            <paramtype>Context &amp;</paramtype>
            <description>
              <para>The context in which the expression should be evaluated.</para>
            </description>
          </parameter>
        </signature>
        <signature>
          <type>typename <classname>proto::result_of::eval</classname>&lt; Expr, Context &gt;::type</type>
          <template>
            <template-type-parameter name="Expr"/>
            <template-type-parameter name="Context"/>
          </template>
          <parameter name="expr">
            <paramtype>Expr &amp;</paramtype>
          </parameter>
          <parameter name="context">
            <paramtype>Context const &amp;</paramtype>
          </parameter>
        </signature>
        <purpose>Evaluate a given Proto expression with a given context. </purpose>
        <returns>
          <para>
            <computeroutput>typename Context::template eval&lt;Expr&gt;()(expr, context)</computeroutput>
          </para>
        </returns>
      </overloaded-function>
    </namespace>
  </namespace>
</header>
